Heat pumps for simultaneous cooling and heating



J- R. HARNISH BEMfiEQ HEAT PUMPS FOR SIMUL'I'ANEOUS COOLING AND HEATING3 Sheets-Sheet 2 Aug". 9, 1966 Filed May 12, 1964 U A; Ff mmumm {M20 HO3 A wEmO mnm mum& NJ J 3,264,839 HEAT PUMPS FOR SIMULTANEOUS 000mm ANDHEATING :5 Sheets-Sheet 3 J. R- HARNISH Aug. 9, 1966 Filed May 12,

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United States Patent 3,264,839 HEAT PUMPS FUR SHMULTANEQUS COOMNG ANDHEATING James R. lillarnish, Staunton, Va., assignor to WestinghouseElectric Corporation, Pittsburgh, Pa, a corporation of PennsylvaniaFiled May 12, 1964, Ser. No. 367,287 31 Claims. (Cl. 6216ll) Thisinvention relates to heat pumps that are used to cool indoor air inparts of buildings, and to simultaneously heat indoor air in other partsof the buildings.

A heat pump used for cooling and heating indoor air simultaneously indifferent parts of a building, has an indoor heat exchanger thatoperates as a condenser, and has another indoor heat exchanger thatoperates as an evaporator. My US. Patent No. 3,109,298 discloses such aheat pump which, when the cooling load is greater than the heating load,operates an outdoor air heat exchanger as an additional condenser, andwhen the heating load is greater than the cooling load, operates theoutdoor air heat exchanger as an additional evaporator. In such a heatpump, the refrigerant flow through the outdoor air heat exchanger isalways in the same direction, requiring that both lines of the outdoorair heat exchanger serve as liquid and vapor lines which have to berelatively large, and require a relatively large charge of refrigerant.Unevaporated refrigerant is stored in a surge drum, and a liquid pumpoperates continuously during both cycles, to pump liquid from the surgedrum to the heat exchangers that are operating as evaporators.

This invention is an improvement over that of my patent in that reversalvalve means is used to reverse the flow of refrigerant, between cycles,through the outdoor air heat exchanger so that one line of the latteralways serves as a liquid. line, and its other line always serves as avapor line. The liquid line, therefore, can be smaller and require lessinsulation than either line of the outdoor air heat exchanger of mypatent, and a smaller refrigerant charge can be used. Another advantageof the present invention over that of my patent is that its liquid pumpneed not operate continuously when the cooling load is greater than theheating load.

Another feature of this invention is that controls are provided whichdetermine when the cooling load or the heating load is greater, andwhich automatically use the outdoor heat exchanger as a condenser whenthe cooling load is greater, and which automatically use the outdoorheat exchanger as an evaporator when the heating load is greater.

An object of this invention is to improve heat pumps that are used tocool indoor air in portions of buildings and simultaneously heat indoorair in other portions of the buildings.

Another object of this invention is to reduce the costs of heat pumpsthat are used to cool indoor air in portions of buildings andsimultaneously heat indoor air in other portions of the buildings.

Another object of this invention is to defrost the outdoor heatexchanger of a heat pump used for simultaneously cooling and heatingindoor air.

Another object of this invention is to provide means for determiningautomatically when the cooling load of a heat pump is greater than itsheating load, and vice versa, and which control the operation of theheat pump.

FIG. 1 is a diagrammatic view of a heat pump embodying this invention;

FIG. 2 is an enlarged view, in section, of the main expansion valve andof its pilot valve, and of their connections;

FIG. 3 is a circuit schematic of a portion of the control circuit of theheat pump;

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FIG. 4 is a simplified circuit schematic of the other portion of thecontrol circuit;

FIG. 5a is a diagrammatic view of the defrost relay;

FIG. 5b is a diagrammatic view of the compressor motor starter;

FIG. 50 is a diagrammatic view of the fan motor starter, and

FIG. 5d is a diagrammatic view of the pump motor starter.

On FIG. 1, the solid line arrows indicate the refrigerant flow when thecooling load is the greater; the dashed line arrows indicate therefrigerant flow when the heating load is greater, and the dash-dot linearrows indicate the refrigerant flow during defrosting of the outdoorcoil.

A refrigerant compressor C driven by an electric motor CM, is connectedby discharge line 10 to the refrigerant inlet of a shell-and-tubecondenser 11, the refrigerant outlet of which is connected by liquidline 12 and expansion valve 13 to the refrigerant inlet ofshell-and-tube evaporator 14. The refrigerant outlet of the evaporator14 is connected through line 16 and pressure regulating valve V6 intoline 17 which connects refrigerant reversal valve RV to surge drum 2%.The line 17 contains a control SPC responsive to pressure therein, andwhich has a switch SPCS which closes when the pressure is reduced to apredetermined minimum. The valve V6 maintains an evaporator temperatureabove 32 F. for preventing freezing of the water that the evaporator 14chills. The drum 20 is connected by line 21 to the suction side of thecompressor C. The discharge line 10 is also connected to the reversalvalve RV, and through the latter and line 24 to outdoor coil 25 when thecooling load is greater than the heating load as will be describedlater. An outdoor air fan OF driven by an electric motor OFM, movesoutdoor air over the coil 25 when the motor OFM is energized. Liquidfrom the outdoor coil 25 when it is operating as a condenser, flowsthrough line 27, main expansion valve 28 and lines 2930 into therefrigerant inlet of the evaporator 14.

The surge drum 20 is connected by liquid line 31 to the inlet of liquidpump P which is driven by an electric motor PM. The outlet of the pump Pis connected through lines 32 and 33, valve V1 controlled by solenoidS1, check valve 34 and the line 34 to the refrigerant inlet of theevaporator 14. The outlet of the pump P is also connected through theline 32, valve V3 controlled by solenoid S3, and check valve 35 to theline 27 for supplying liquid to the outdoor coil 25 when it is operatingas an evaporator as will be described later. The line 12 from thecondenser 11 is connected through line 36 and check valve 37 to theoutlet of the pump P.

The expansion valve 13 has a diaphragm chamber 38, the upper portion ofwhich, above a diaphragm, which is not shown, is connected by a smalltube 3? to thermal bulb 41 in contact with the line 12, and the lowerportion of which, below the diaphragm, is connected by equalizer tube 41to the interior of the line 12. The valve 13 responds to the temperatureand pressure of the liquid in the line 12, and maintains a predeterminedamount of subcooling which may be 10 F., at a condensing temperature ofF., as disclosed in my copending application, Serial No. 309,861, filedSept. 18, 1963.

The main expansion valve 28 is controlled by a conventional expansionvalve 42 acting as a pilot valve, as shown by FIG. 2. The inlet of thevalve 42 is connected through an orifice 43, line 44 and valve V2controlled by a solenoid S2, to the line 27. The outlet of the valve 42is connected by line 46 to the line 29. The valve 42 has a casing 52around a diaphragm chamber 53. A diaphragm 5 1 extends across the centerof the chamber 53, and is connected at its center to the upper end ofrod of valve piston 56. The piston 56 is above a valve opening 57 in apartition 59 extending between the inlet and outlet of the valve 42. Acoiled spring 58 extends between the bottom of the chamber 53 and thetop of the piston 56, and biases the piston 56 towards closed position.The chamber 53 above the diaphragm 54 is connected by a small tube 60 toa thermal bulb 61 in contact with the line 27. The chamber 53 below thediaphragm 54 is connected by an equalizing tube 62 to the interior ofthe line 27. Liquid from the line 27 when the outdoor coil 25 isoperating as a condenser, flows through the valve V2 and the orifice 43into the valve 42. The main expansion valve 28 has a casing 67containing a piston 68 connected at its center to the upper end of apiston rod 69 which has a valve piston 70 on its lower end. A partition71 extends between the inlet and outlet of the valve 28, and has a valveopening 72 therein above the piston 70. The top of the valve 28 abovethe piston 68 is connected by line 75 to the inlet of the valve 42. Acoiled spring 73 extends between the bottom of the piston 70 and thebottom of the casing 67, and biases the piston 70 towards closedposition.

In the operation of the valves 28 and 42, a decrease in the amount ofsubcooling of the liquid in the line 27 when it is operating as a liquidline, below, for example, 10 F., at a condensing temperature of 100 F.,causes the pressure above the diaphragm 54 to increase and therebycauses the diaphragm 54 to move the piston 56 towards its closedposition. This bleeds pressure from above the top of the piston 68 ofthe valve 28 to downstream of the latter, permitting the spring 73 tomove the piston 70 towards closed position so as to back up more liquidfor more subcooling. A valve is connected in a line 86 across the valveV2. The valve 85 has a diaphragm chamber 88 connected by a small tube 89to the interior of the line 86.

The lines 27 and 17 are connected by a line 87 containing a valve V4adjusted by a solenoid S4. A float control 90 responds to refrigerantliquid level in the condenser 11, and has a switch 91 which closes whensuch level is low.

The evaporator 14 has a chilled water outlet connection 119 and a returnwater connection 120 for use with local air cooling coils which are notshown. The connection 120 preferably contains a proportioning thermostat122 connected by a small tube 121 to a bellows 123 although thisthermostat could be in the connection 119. The condenser 11 has a heatedwater outlet connection 126 and a return water connection 126 for usewith local air heating coils which are not shown. Preferably theconnection 126 contains a proportional thermostat 127 connected by asmall tube 128 to a bellows 145, although the thermostat 127 could be inthe connection 125.

The reversal valve RV is adjusted by a solenoid S5 when the latter isenergized, to operate the outdoor coil 25 as an evaporator, and isadjusted by a solenoid S6 when the latter is energized, to operate thecoil 25 as a condenser. The solenoid S5 is deenergized when the solenoidS6 is energized, and vice versa, as will be explained later.

The compressor motor CM, the fan motor OFM and the pump motor PM havestarters CMS, OFMS and PMS respectively.

A defrost control DC responds to air pressure drop across the coil 25caused by the formation of a substantial amount of frost thereon whenthe coil 25 is operating as an evaporator at low outdoor temperatures,and has a normally open switch DCS which closes when the coil 25 needsto be defrosted. A defrost limit control DLC responds to refrigerantpressure within the coil 25, and has a normally closed switch DLCS whichopens when the pressure within the coil 25 rises as a result of thefrost having melted from it.

As shown by FIG. 3, a conventional sequencer SEQ has cam discs 101 and102 rotated by an electric motor SM. The motor SM has a forward fieldwinding 105, and a the ID reverse field winding 106. The winding 105 isconnected at one end through limit switch 107 and wire 108 to switchBRS2 of a conventional balancing relay BRl. The winding 106 is connectedat one end through limit switch 109 and wire 110 to switch BRS1 of therelay BRl. The other ends of the windings 105 and 106 are connected bywire 111 to electric supply line L2. The relay BR1 has an armature 112connected to electric supply line L1, and which is moved by a pivoted,U-shaped core 113 having a winding 114 on one leg, and a winding 115 onits other leg. Corresponding ends of the windings 114 and 115 areconnected to the ends of potentiometer 116. The other ends of thewindings 114 and 115 are connected to the ends of potentiometer 118.Slider 119 of the potentiometer 118 is electrically connected to theelectric line L1, and is mechanically connected to the bellows 145. Thelatter is also connected to slider 124 of potentiometer 155, whichslider is electrically connected to the electric line L1. The ends ofthe potentiometer 12 5 are connected through switches R282 and R283 ofrelay R2 to corresponding ends of windings 156 and 157 on the legs ofpivoted, U-shaped core 158 of conventional balancing relay BR2 ofconventional, proportioning type, step controller PSC, and throughswitches R151 and R183 of relay R1 to the ends of potentiometer 129.Armature of the core 158 is connected to the electric line L1, and ismovable to close switch CS1 or CS2 which are connected through limitswitches 131 and 132 respectively, to corresponding ends of forwardfield winding 133 and reverse field winding 134 of motor 135. The otherends of the windings 133 and 134 are connected to the electric line L2.Sliders 136 and 137 of the potentiometers 116 and 129 respectively, areelectrically connected to the electric lines L2 and L1 respectively, andare connected mechanically to the bellows 123. The other ends of thewindings 156 and 157 are connected to the ends of potentiometer 140,slider 147 of which is movable by the motor 135. The motor also rotatescam discs 138, 139, 140 and 141 which have cam followers 151, 152, 153and 154 respectively. The cam follower 151 closes switch PSCSl when themotor 135 starts to rotate in a counterclockwise direction with respectto FIG. 3, at the start of a cycle, and maintains the switch PSCSIclosed until the end of the cycle. The cam followers 152, 153 and 154successively close switches PSCSZ, PSCS3 and PSCS4 respectively, duringcontinued rotation of the motor 135 in the counterclockwise direction,and successively open such switches when the motor 135 rotates in theopposite direction. As shown by FIG. 4, the switches PSCS2, PSCS3 andPSCS4 are electrically connected to solenoids S7, S8 and S9respectively. Such switches when closed energize such solenoids whichoperate the conventional loadersunloaders of cylinders C2, C3 and C4 ofthe compressor C, which loaders-unloaders are not shown. Cylinder C1 ofthe compressor C has no such loader-unloader. The solenoids S7, S8 andS9, when energized, load their respective cylinders C2, C3 and C4, andwhen deenergized, unload their respective cylinders.

The heating control thermostat 127 and the cooling control thermostat122 adjust the potentiometers 155 and 129 respectively, in the usualmanner to accomplish control of the compressor motor, and the compressorcylinder loading and unloading. This invention adds a secondpotentiometer 118 to the thermostat 127, a second potentiometer 116 tothe thermostat 122, the sequencer SEQ, and the relays R1 and R2, anduses the switches R152 and R183 of the cooling control relay R1 to placethe cooling control thermostat 122 in control of the cylinder loadingand unloading when the cooling load is greater than the heating load,and uses the switches R2S2 and R283 of the heating control relay R2 toplace the heating control thermostat 127 in control of the cylinderloading and unloading when the heating load is greater than the coolingload.

Referring now to FIG. 4, the switch PSCS1 is connected in series withswitch R381 of defrost relay R3, and the fan motor starter OFMS to theelectric lines L1. The compressor motor starter CMS is connected inparallel with OFMS. The solenoid S7 is connected in series with switchesP8C82, R381 of the relay R3 and PSCS1 to the electric lines. Thesolenoid S8 is connected in series with the switches PSC83, R381 of therelay R3 and P8C81 to the electric lines. The solenoid S9 is connectedin series with the switches P8C84, R381 of the relay R3 and P8C81 to theelectric lines. The solenoid S1 is connected in series with the switchesR181 of the relay R1, R381 of the relay R3 and P8C81 to the electriclines. The solenoid 83 is connected in series with the switches R284 ofthe relay R2, R381 of the relay R3 and P8C81 to the electric lines. Thesolenoid 85 is connected in parallel with the solenoid 83. The pumpmotor starter PMS is connected in one path in series with the switchesR384 of the relay R3, R185 of the relay R1, SPCS of the control SPC,R381 of the relay R3 and P8CS1 to the electric lines, and in anotherpath is connected in series with the switches 91 of the float control 90and R385 of the relay R3 to the electric lines. Switch R287 of the relayR2 is connected across the series connection of the switches SPCS andR185. The defrost relay R3 is connected in series with the switches DLCSof the defrost limit control DLC, R382 of the relay R3 and R286 of therelay R2 to the electric lines. The solenoid S4 is connected in parallelwith the relay R3. The switch DCS of the defrost control DC is connectedin parallel with the series connection of the switches R382 and DLCS.The solenoid S6 is connected in series with the switch R184 of the relayR1 to the electric lines. Switch R383 of the relay R3 is connected inparallel with the switch R184. The solenoid 82 is connected in serieswith the switch ODTS of the outdoor thermostat ODT across the solenoid86. Switch CMSS of the compressor motor starter CMS is connected inseries with the compressor motor CM to the electric lines. Switch OFMSSof the fan motor starter OFMS in connected in series with the fan motorOFM to the electric lines. Switch PMSS of the pump motor starter PMS isconnected in series with the pump motor PM to the electric lines.

Operation When the heating load becomes greater than the cooling load,the heating control thermostat 127 moves through the bellows 1-45, theslider 119 of the potentiometer 118 nearer its 100% point than thecooling control thermostat 122 moves through the bellows 123, the slider136 of the potentiometer 116. This causes more current to flow throughthe winding 114 of the relay BR I than flows through its winding \1'15,causing the armature 112 to close the switch BR SZ, supplying current tothe field winding 105 of the sequencer motor SM, causing the latter torotate in a clock-wise direction with respect to FIG. 3, and to rotatethe cam discs 1 and 102 in the same direction. The cam follower 103closes the switch SMSl, and shortly thereafter, the cam follower 104closes the switch SMSZ, connecting the heating control relay R2 to theelectric lines. The now energized relay R2 opens its switch R281disconnecting the cooling control relay R1 from the electric lines, andcloses its switches R282, R283, R284, R285, R286 and R287. The switchR285 is a holding circuit switch connected across the switch SMS2 formaintaining the relay R2 energized for a short period after the motor 8Mreverses as will be described later, and the switch SMSZ opens. Byoperating the switches SMS1 and SMS2 in sequence, a time delay isprovided so that the system will not continuously cycle back and forthwhen the heating and cooling loads are nearly in balance. The now closedswitches R282 and R283 connect the potentiometer 125 to the balancingrelay BR2, causing the motor .135 to be energized and to rotate in adirection to load or unload cylinders of the compressor C as required byits heating load. The closed switch R284 energizes through the closedswitch R38 1 of the relay R3, the solenoid which adjusts the reversalvalve RV to the position for operating the outdoor coil 25 as anevaporator, and energizes the solenoid 83 which opens the valve V3 toconnect the pump P to the outdoor coil 25. The closed switch R287 isconnected across the switches SPCS and R185, and closes the energizingcircuit of the pump motor starter PMS, starting the pump. The closedswitch R286 connects the defrost initiating switch DCS through thedefrost relay R3, to the electric line L1 -for permitting defrosting ofthe coil 25 when necessary, as will be described later.

Discharge gas from the compressor C flows through the line 10 into thecondenser 11. Liquid refrigerant from the condenser 11 flows through theexpansion valve 13 into the evaporator 14. Gas and any unevaporatedliquid from the evaporator 14 flows through the line .16, the pressureregulating valve V6 and the line 17 into the surge drum 20, the gasseparated from the liquid within the surge drum flowing through thesuction gas line 21 to the compressor C. The pump P supplies liquid fromthe surge drum into the outdoor coil 25 which is now operating as anevaporator. The valve V1 is closed at this time through its solenoid 81being deenergized by the open switch R 181 of the now deenergized relayR1. Gas and any unevaporated liquid from the coil 25 flows through theline 24 and the reversal valve RV into the surge drum 20, being mixedtherein with refrigerant from the evaporator 14.

When the cooling load becomes greater than the heating load, the coolingcontrol thermostat 122 moves through the bellows 123, the slider 136 ofthe potentiometer 1'16 nearer its point than the heating controlthermostat moves the slider 119 of the potentiometer 1118. This causesmore current to -flow through the winding of the relay BRl than flowsthrough its winding 114, causing its armature 112 to close the switchBR81, supplying current to the field winding 106 of the sequencer motor8M, causing the latter to rotate the cam discs 10 1 and 102 in acounterclockwise direction so that the cam follower 104 opens the switchSMSZ, and shortly thereafter the cam follower 10'3 opens the switch 8M81 for deenergizing the heating control relay R2. The holding circuitswitch R285 of the relay R2, connected across the switch 8M82, maintainsthe relay R2 energized until the switch 8M81 opens, providing time delayduring the change-over for permitting the system operation to stabilize,and to avoid hunting between cycles.

The deenergized relay R2 closes its switch R281, connecting the coolingcontrol relay R1 to the electric lines, and opens its switches R282,R283, R284, R285, R286 and R287 which deenergize the previouslydescribed circuits in which they are connected. The now energized relayR1 closes its switches R181, R182, R183, R184 and R185. The closedswitch R181 energizes the solenoid 81 which opens the valve V1permitting the pump P to pump liquid refrigerant from the surge drum 20into the evaporator 14. The valves V3 and V4 are closed at this timesince their solenoids S3 and 84 respectively, are deenergized throughthe now open switches R284 and R286 respectively. The now closedswitches R182 and R183 connect the potentiometer 129 to the windings 156and 157 of the relay B R2, causing the motor to rotate in a direction toload or unload cylinders of the compressor C as required by the coolingload under control of the thermostat 122. The now closed switch R184 ofthe relay R1 energizes the solenoid S6 to adjust the reversal valve RVto route discharge gas from the line 10, through the line 24 into theoutdoor coil 25 to operate the later as a condenser. The now closedswitch R185 of the relay R1 permits energization of the pump motorstarter PMS when the switch SPCS of the valve SPC closes.

The compressor C supplies discharge gas through the line 10 into thecondenser 11 and the reversal valve RV, flowing from the latter throughthe line 24 into the outdoor coil 25 operating as a condenser. Liquidrefrigerant from the condenser 11 flows through the line 12 andexpansion valve 13 into the evaporator 14. Liquid refrigerant from theoutdoor coil 25 flows through the line 27, expansion valve 28 and line29 into the evaporator 14. Liquid refrigerant from the surge drum 20flows through the line 31 into the pump P, and from the latter when itis operating, through the valve V1 and line 30 into the evaporator 14.The pump motor starter PMS is energized to start the pump motor PM bythe pressure control SPC in the line .16 when the pressure within thelatter falls to a predetermined value, so as to prevent the evaporator14 from starving, the switch SPCS being closed at such time, andenergizing the starter PMS through the switch R155 of the relay R1.

Gas and any unevaporated liquid from the evaporator 14 flows through theline 16 and the valve V6 into the surge drum 20. Gas separated from theliquid within the surge drum flows through the suction gas line 21 tothe compressor C.

When the outdoor temperature is low, the increased condensing capacityof the outdoor coil 25 may greatly lower the condensing temperature,preventing the condenser 11 from receiving sufficient heat to satisfythe heating load. To prevent this, the pressure regulating valve 85 isprovided in the line connecting the pilot valve 42 to the line 27, andis preset to maintain a sufficiently high pressure to prevent theexpansion valve 28 from opening until suflicient liquid has backed upwithin the outdoor coil 25 to reduce its condensing capacity. The valveV2 is connected across the valve 85, and its solenoid S2 is energized bythe closing of the switch ODTS of the outdoor thermostat CDT, to openthe valve V2 when the outdoor temperature is high enough to reduce theheating load. This permits the coil 25 to operate at lower condensingtemperatures, improving the system efficiency.

At low outdoor temperatures when the outdoor coil 25 is operating as anevaporator, frost may form on the coil 25. When suflicient frost hasformed on the coil 25 to affect its performance, the increased airpressure drop across the coil 25 causes the switch DCS of the defrostcontrol DC to close and energize the defrost relay R3, and the solenoidS4. The energized solenoid S4 opens the valve V4. The energized relay R3closes its switches R382, R383 and R354 and opens its switches R351 andR384. The open switches R381 and R384 open the energizing circuits ofthe motor starters CMS and OFMS, the solenoids S7, S8, S9, S1 and S5,and that portion of the energizing circuit of the pump motor starter PMSwhich includes the switches SPCS, R185 and R2S7. The compressor and fanmotors are turned off. The pump motor starter PMS can only be energizedthrough the switches 91 of the float control 90, and R385 of the relayR3. The closed switch R382 is a holding circuit switch connected acrossthe switch DCS for maintaining the defrost relay R3 energized when theswitch DCS opens as a result of the stopping of the fan motor OFM, andthe cessation of air flow through the coil 25. The closed switch R3S3energizes the solenoid S6 which adjusts the reversal valve RV to supplygas from the condenser 11 which is now operating as an evaporator,through the line 24 into the coil 25 to operate the latter as acondenser for melting the frost thereon. Liquid from the coil 25 flowsthrough the line 87 and the now open valve V4, and the pressure controlSPC into the surge drum 20. The closed switch R3S5 establishes a circuitto the float switch 91, permitting the latter to energize the pump motorstarter PMS to operate the pump P intermittently as the refrigerantliquid level in the condenser 11 falls and rises. Liquid from the surgedrum 20 is pumped by the pump P, when the latter operates, through thecheck valve 37 and the lines 36 and 12 into the condenser 11 operatingas an evaporator. The pump P is controlled by the float switch 91 tokeep some of the condenser tubes immersed in liquid refrigerant. Thevalves V1 and V3 are closed at this time as a result of their solenoidsS1 and S3 respectively, being deenergized by the now open switches R351and R3S4 of the defrost relay R3.

When the frost has melted from the coil 25, the increased refrigerantpressure within the latter causes the switch DLCS of the defrost limitcontrol DLC to open, deenergizing the defrost relay R3 and the solenoidS4. The solenoid S4 closes the valve V4. The deenergized relay R3 opensits switches R352, R383 and R385, and closes its switches R381 and R3S4,returning the system back to normal operation with the outdoor air coil25 operating as an evaporator as it was when the frost formed on it.

In the annexed claims, heat sink exchanger is defined as a heatexchanger exposed to a heat absorbing or heat dissipating source.

I claim:

1. A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in another portion of the building,comprising a refrigerant compressor; a condenser for heating fluid forsupply to local air heating units, and having its refrigerant inletconnected to the discharge side of said compressor; an evaporator forchilling fluid for supply to local air cooling units, and having itsrefrigerant inlet connected to the refrigerant outlet of said condenser;a surge drum having a gas outlet connected to the suction side of saidcompressor, and having a gas and unevaporated liquid inlet connected tothe refrigerant outlet of said evaporator; a pump having an inletconnected to receive liquid refrigerant from said drum, and having anoutlet connected to said inlet of said evaporator; a heat sinkexchanger, and having one side connected to said inlet of saidevaporator and to said outlet of said pump; reversal valve meansconnected to said discharge side of said compressor, to the other sideof said heat exchanger, and to said inlet of said drum; means when thecooling load is greater than the heating load for adjusting said valvemeans to route gas from said discharge side of said compressor to saidother side of said heat exchanger, and for routing liquid from said pumpto said inlet of said evaporator; and means when the heating load isgreater than the cooling load for routing liquid from said pump to saidone side of said heat exchanger, and for adjusting said valve means toroute gas and unevaporated liquid from said other side of said heatexchanger to said inlet of said drum.

2. A heat pump as claimed in claim 1 in which control means is providedfor sensing when the cooling load is greater than the heating load, .andfor sensing when the heating load is greater than the cooling load, andin which means is provided for operating with said control means saidmeans for adjusting said valve means to route discharge gas from saiddischarge side of said compressor to said other side of said heatexchanger, and said means for routing liquid from said pump to saidinlet of said evaporator, when the cooling load is greater than theheating load, and in which means is provided for operating with saidcontrol means said means for routing liquid from said pump to said oneside of said heat exchanger, and said means for adjusting said valvemeans to route gas and unevaporated liquid from said other side of saidheat exchanger to said inlet of said drum, when the heating load isgreater than the cooling load.

3. A heat pump as claimed in claim 2 in which said pump has drivingmeans, and in which means including means responsive to the pressure ofthe refrigerant in the connection of said outlet of said evaporator tosaid inlet of said drum is provided for energizing said drivrng means.

4. A heat pump as claimed in claim 3 in which the connection of said oneside of said heat exchanger to said inlet of said evaporator includesexpansion means responsive to the temperature and pressure of therefrigerant at said one side of said heat exchanger.

5. A heat pump as claimed in claim 4 in which said connection of saidone side of said heat exchanger to said inlet of said evaporatorincludes means for preventing said expansion means from opening below apreset condensing pressure in said heat heat exchanger when said valvemeans is adjusted to route discharge gas from said compressor to saidheat exchanger, and in which means including means responsive to outdoorair temperature is provided for disabling said means for preventing saidexpansion means from opening.

6. A heat pump as claimed in claim it in which control means is providedfor sensing when the cooling load is greater than the heating load, andfor sensing when the heating load is greater than the cooling load, inwhich means is provided for operating with said control means said meansfor adjusting said valve means to route discharge gas from saiddischarge side of said compressor to said other side of said heatexchanger, and said means for routing liquid from said pump to saidinlet of said evaporator, when the cooling load is greater than theheating load, in which means is provided for operating with said controlmeans said means for routing liquid from said pump to said one side ofsaid heat exchanger, and said means for adjusting said valve means toroute gas and unevaporated liquid from said other side of said heatexchanger to said inlet of said drum, when the heating load is greaterthan the cooling load, and in which the connection of said one side ofsaid heat exchanger to said inlet of said evaporator includes expansionvalve means responsive to the temperature and pressure of therefrigerant at said one side of said heat exchanger.

7. A heat pump as claimed in claim 6 in which means is provided forpreventing said expansion valve means from opening below a presetcondensing pressure in said heat exchanger when said reversal valvemeans is adjusted to route discharge gas from said compressor to saidheat exchanger, and in which means including means responsive to outdoortemperature is provided for dis abling said means for preventing saidexpansion valve means from opening.

8. A heat pump as claimed in claim 1 in which said pump has drivingmeans, and in which means including means responsive to the pressure ofthe refrigerant in the connection of said outlet of said evaporator tosaid inlet of said drum is provided for energizing said driving means.

9. A heat pump as claimed in claim 8 in which the connection of said oneside of said heat exchanger to said inlet of said evaporator includesexpansion valve means responsive to the temperature and pressure of therefrigerant at said one side of said evaporator.

10. A heat pump as claimed in claim 9 in which means is provided forpreventing said expansion valve means from opening below a presetcondensing pressure in said heat exchanger when said reversal valvemeans is adjusted to route discharge gas from said compressor to saidheat exchanger, and in which means including means responsive to outdoortemperature is provided for disabling said means for preventing saidexpansion valve means from opening.

11. A heat pump as claimed in claim 1 in which the connection of saidone side of said heat exchanger to said inlet of said evaporatorincludes expansion valve means responsive to the temperature andpressure of the refrigerant at said one side of said heat exchanger.

12. A heat pump as claimed in claim 11 in which means is provided forpreventing said expansion valve means from opening below a presetcondensing temperature in said heat exchanger when said reversal valvemeans is adjusted to route discharge gas from said compressor to saidheat exchanger, and in which means including means responsive to outdoortemperature is provided for disabling said means for preventing saidexpansion valve means from opening.

13. A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in another portion of the building,comprising a refrigerant compressor; a condenser for heating fluid forsupply to local air heating units, said condenser having a fluid outletconnection and a fluid return connection, and having its refrigerantinlet connected to the discharge side of said compressor; an evaporatorfor chilling fluid for supply to local air cooling units, saidevaporator having a fluid outlet connection and a fluid returnconnection, and having its refrigerant inlet connected to therefrigerant outlet of said condenser; reversal valve means; a heat sinkexchanger, said heat exchanger having one side connected to saidrefrigerant inlet of said evaporator; means connecting said reversalvalve means to said discharge side of said compressor, to the suctionside of said compressor, and to the other side of said heat exchanger;and means including means responsive to the temperatures of the fluidsat one of said connections of said condenser and at one of saidconnections of said evaporator, for sensing when the cooling load isgreater than the heating load and when the heating load is greater thanthe cooling load, and for adjusting said reversal valve means to routedischarge gas from said compressor to said other side of said heatexchanger when the cooling load is greater than the heating load, andfor adjusting said reversal valve means to route gas from said otherside of said heat exchanger to said suction side of said compressor whenthe heating load is greater than the cooling load.

14. A heat pump as claimed in claim 13 in which the connection of saidone side of said heat exchanger to said refrigerant inlet of saidevaporator includes refrigerant expansion valve means responsive to thetemperature and pres-sure of the refrigerant at said one side of saidheat exchanger.

15. A heat pump as claimed in claim 14 in which means is provided forpreventing said expansion valve means from opening below a presetcondensing temperature in said heat exchanger when said reversal valvemeans is adjusted to route discharge gas from said compressor to saidheat exchanger, and in which means including means responsive to outdoortemperature is provided for disabling said means for preventing saidexpansion valve means from opening.

16. A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in another portion of the building,comprising a refrigerant compressor; a condenser for heating fluid forsupply to local air heating units, said condenser having a fluid outletconnection and a fluid return connection; an evaporator for chillingfluid for supply to local air heating units, said evaporator having afluid outlet connection and a fluid return connection; a surge drum;refrigerant lines connecting said compressor, condenser, evaporator anddrum in a closed refrigerant circuit; said drum having a gas outletconnected to the suction side of said compressor; a heat sink exchanger;a pump for receiving liquid refrigerant from said drum; control meansincluding means responsive to the temperatures of the fluid at one ofsaid connections of said condenser and at one of said connections ofsaid evaporator, for sensing when the cooling load is greater than theheating load and when the heating load is greater than the cooling load;means operated !by said control means to route refrigerant from saidcompressor to said heat exchanger and to route liquid from said pump tosaid evaporator when the cooling load is greater than the heating load;and means operated by said control means for routing liquid from saidpump to said heat exchanger and for routing refrigerant from said heatexchanger to said drum when the heating load is greater than the coolingload.

17. A heat pump as claimed in claim 16 in which said pump has drivingmeans, in which the refrigerant outlet of said evaporator is connectedto a gas and unevaporated liquid inlet of said drum, and in which meansincluding means responsive to the pressure of the refrigerant in theconnection of said outlet of said evaporator to said inlet of said drumis provided for energizing said driving means.

18. A heat pump as claimed in claim 17 in which said heat exchanger isconnected to said inlet of said evaporator for supplying liquidrefrigerant to said evaporator when said heat exchanger is supplied withrefrigerant from said compressor, in which expansion valve meansresponsive to the temperature and pressure of the refrigerant in theconnection of said heat exchanger to said inlet of said evaporator isprovided in said last mentioned connection.

19. A heat pump as claimed in claim 18 in which means is provided forpreventing said expansion valve means from opening below a presetcondensing pressure in said heat exchanger when said heat exchanger issupplied with refrigerant from said compressor, and in which meansincluding means responsive to outdoor temperature is provided fordisabling said means for preventing said expansion valve means fromopening.

20. A heat pump as claimed in claim 16 in which said heat exchanger isconnected to said inlet of said evaporator for supplying liquidrefrigerant to said evaporator when said heat exchanger is supplied withrefrigerant from said compressor, and in which expansion valve meansresponsive to the temperature and pressure of the refrigerant in theconnection of said heat exchanger to said inlet of said evaporator isprovided in said last mentioned connection.

21. A heat pump as claimed in claim 20 in which means is provided forpreventing said expansion Valve means from opening below a presetcondensing pressure in said heat exchanger when said heat exchanger issup plied with refrigerant from said compressor, and in which meansincluding means responsive to outdoor temperature is provided fordisabling said means for preventing said expansion valve means fromopening.

22. A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in another portion of the building,comprising a refrigerant compressor; a motor for driving saidcompressor; a condenser for heating fluid for supply to local airheating units; an evaporator for chilling fluid for supply to local aircooling units, a surge drum; refrigerant lines connecting saidcompressor, said condenser, said evaporator in a closed refrigerantcircuit; a heat sink exchanger exposed to outdoor air; a fan for movingoutdoor air over said heat exchanger; a pump for receiving liquidrefrigerant from said drum; means for routing liquid from said pump tosaid heat exchanger and for routing gas and unevaporated liquid fromsaid heat exchanger to said drum when the heating load is greater thanthe cooling load; and means for melting frost when it forms on said heatexchanger, including means for routing liquid from said pump to saidcondenser, including means for discontinuing the routing of liquid fromsaid pump to said heat exchanger, including means for stopping said fanand compressor motors, and including means for routing liquid from saidheat exchanger to said drum.

23. A heat pump as claimed in claim 22 in which a motor is provided fordriving said pump, and in which means including means responsive to therefrigerant liquid level in said condenser is provided for energizingsaid last mentioned motor.

24. A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in another portion of the building,comprising a refrigerant compressor; a motor for driving saidcompressor; a condenser for heating fluid for supply to local airheating units; an evaporator for chilling fluid for supply to local aircooling units; a surge drum; reversal valve means; refrigerant linesconnecting said compressor, said condenser, said evaporator, said drumand said reversal valve in a closed refrigeration circuit; a pump forreceiving liquid refrigerant from said drum; a heat sink exchangerexposed to outdoor air; a fan for moving outdoor air over said heatexchanger; a motor for driving said fan; means when the heating load isgreater than the cooling load for routing liquid from said pump to saidheat exchanger, and including said reversal valve means for routing gasand unevaporated liquid from said heat exchanger to said drum; and meansfor melting frost when it forms on said heat exchanger, including meansfor stopping said fan and compressor motors, including means fordiscontinuing the routing of liquid from said pump to said heatexchanger, including means for routing liquid from said pump to saidcondenser, including said reversal valve means for routing gas from saidcondenser to said heat exchanger, and including means for routing liquidfrom said heat exchanger to said drum.

25. A heat pump as claimed in claim 24 in which a motor is provided fordriving said pump, and in which means including means responsive to therefrigerant liquid level in said condenser is provided for energizingsaid last mentioned motor.

26. A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in another portion of the building,comprising a refrigerant compressor; a condenser for heating fluid forsupply to local air heating units, said condenser having a fluid outletconnection and a fluid return connection; a first thermostat in one ofsaid connections; an evaporator for chilling fluid for supply to localair cooling units, said evaporator having a fluid outlet connection anda fluid return connection; a second thermostat in one of saidconnections of said evaporator; a first potentiometer having a slideradjusted by said first thermostat; a second potentiometer having aslider adjusted by said second thermostat; means connecting saidcompressor, said condenser and said evaporator in a closed refrigerationcircuit; a heat sink exchanger; a balancing relay having first andsecond windings, one end of said first winding being connected to oneend of said first potentiometer, the other end of said first windingbeing connected to one end of said second potentiometer, one end of saidsecond winding being connected to the other end of said firstpotentiometer, the other end of said second winding being connected tothe other end of said second potentiometer; electric supply linesconnected to said sliders; a first switch closed by said relay when thecurrent through said first winding is larger than the current throughsaid second winding; a second switch closed by said relay when thecurrent through said second winding is larger than the current throughsaid first winding; cooling control relay means having switches; heatingcontrol relay means having switches; means including said first switchfor energizing said heating relay means; means including said secondswitch for energizing said cooling relay means; means for routing liquidrefrigerant from said condenser to said heat exchanger, and for routinggas from said heat exchanger to said compressor; means including saidswitches of said heating relay means for energizing said last mentionedmeans; means for routing discharge gas from said compressor to said heatexchanger, and for routing liquid refrigerant from said heat exchangerto said evaporator; and means including said switches of said coolingrelay means for energizing said last mentioned means.

27. A heat pump as claimed in claim 26 in which a third potentiometer isprovided and which has a slider adjusted by said first thermostat; inwhich a fourth potentiometer is provided and which has a slider adjustedby said second thermostat; in which said supply lines are connected tosaid sliders of said third and fourth potentiometers; in which a secondbalancing relay is provided and which has third and fourth windings;means including another switch of said heating relay means when saidheating relay means is energized, for connecting one end of said thirdwinding to one end of said third potentiometer; means including anotherswitch of said heating relay means when said heating relay means isenergized, for connecting one end of said fourth winding to the otherend of said third potentiometer; means including another switch of saidcooling relay means when said cooling relay means is energized, forconnecting said one end of said third winding to one end of said fourthpotentiometer; means including another switch of said cooling relaymeans when said cooling relay means is energized, for connecting saidone end of said fourth winding to the other end of said fourthpotentiometer; in which a fifth potentiometer is provided with its endsconnected to the other ends of said third and fourth windings; in whicha reversible motor having forward and reverse field windings, and havinga rotor connected to move the slider of said fifth potentiometer, isprovided; in which said second relay has a fifth switch which closeswhen the current through said third winding is larger than the currentthrough said fourth winding, and has a sixth switch which closes whenthe current through said fourth winding is larger than the currentthrough said third winding; means including said fifth switch forenergizing one of said windings of said motor; means including saidsixth switch for energizing the other one of said windings of saidmotor; in which said compressor has a plurality of loaders-unloaders; inwhich a plurality of switches, one for each of said loaders-unloaders,is provided with said switches of said plurality being arranged to beclosed in succession when said rotor rotates in one direction, and to beopened in succession when said rotor rotates in the opposite direction;in which said loaders-unloaders are provided with solenoids foradjusting said loaders-unloaders to loading or unloading positions; andin which means including said last mentioned switches is provided forenergizing said solenoids.

28. A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in an other portion of the building,comprising a refrigerant compressor; a condenser for heating fluid forsupply to local air heating units, said condenser having a fluid outletconnection and a fluid return connection; a first thermostat in one ofsaid connections; an evaporator for chilling fluid for supply to localair cooling units, said evaporator having a fluid outlet connection anda fluid return connection; a second thermostat in one of saidconnections of said evaporator; a first potentiometer having a slideradjusted by said first thermostat; a second potentiometer having aslider adjusted by said second thermostat; means connecting saidcompressor, said condenser and said evaporator in a closed refrigerationcircuit; a heat sink exchanger; a balancing relay having first andsecond windings, one end of said first winding being connected to oneend of said first potentiometer, the other end of said first windingbeing connected to one end of said second potentiometer, one end of saidsecond winding being connected to the other end of said firstpotentiometer, the other end of said second winding being con nected tothe other end of said second potentiometer; electric supply linesconnected to said sliders; a first switch closed by said relay when thecurrent through said first winding is larger than the current throughsaid second winding; a second switch closed by said relay when thecurrent through said second winding is larger than the current throughsaid first winding; a reversible motor having forward and reverse fieldwindings; means including said first switch for energizing one of saidfield windings; means including said second switch for energizing theother one of said field windings; third and fourth switches closed insuccession when said one field winding is energized, and opened insuccession when said other field winding is energized; a cooling controlrelay; a heating control relay; means including said third and fourthswitches for energizing one of said control relays; means when said onecontrol relay is energized, for deenergizing said other control relay;means including switches closed when said cooling relay is energized andincluding means energized when said last mentioned switches are closed,for routing discharge gas from said compressor to said heat exchanger,and routing liquid refrigerant from said heat exchanger to saidevaporator; and means including switches closed when said heating relayis energized and including means energized when said last mentionedswitches are closed, for routing liquid refrigerant from said condenserto said heat exchanger, and routing gas from said heat exchanger to saidcompressor.

29. A heat pump as claimed in claim 28 in which a third potentiometer isprovided and which has a slider adjusted by said first thermostat; inwhich a fourth potentiometer is provided and which has a slider adjustedby said second thermostat; in which said supply lines are connected tosaid sliders of said third and fourth potentiometers; in which a secondbalancing relay is provided and which has third and fourth windings;means including another switch of said heating relay when said heatingrelay is energized, for connecting one end of said third winding to oneend of said third potentiometer; means including another switch of saidheating relay when said heating relay is energized, for connecting oneend of said fourth winding to the other end of said third potentiometer;mean including another switch of said cooling relay when said coolingrelay is energized, for connecting said one end of said third winding toone end of said fourth potentiometer;

means including another switch of said cooling relay when said coolingrelay is energized, for connecting said one end of said fourth windingto the other end of said fourth potentiometer; in which a fifthpotentiometer is provided with its ends connected to the other ends ofsaid third and fourth windings; in which a second reversible motorhaving forward and reverse field windings is provided, said second motorhaving a rotor connected to move the slider of said fifth potentiometer;in which said second relay has a fifth switch which closes when thecurrent through said third winding is larger than the current throughsaid fourth winding, and has a sixth switch which closes when thecurrent through said fourth winding is larger than the current throughsaid third winding; means including said fifth switch for energizing oneof said windings of said second motor; means including said sixth switchfor energizing the other one of said windings of said second motor; inwhich said compressor has a plurality of loaders-unloaders; in which aplurality of switches, one for each of said loaders-unloaders, isprovided with said switches of said plurality being arranged to beclosed in succession when said rotor of said second motor rotates in onedirection, and to be opened in succession when said rotor of said secondmotor rotates in the opposite direction; in which saidl-oaders-unloaders are provided with solenoids for adjusting saidloaders-unloaders to loading or unloading positions; and in which meansincluding said last mentioned switches is provided for energizing saidsolenoids.

30, A heat pump for cooling indoor air in a portion of a building andsimultaneously heating indoor air in another portion of the building,comprising a refrigerant compressor; a condenser for heating fluid forsupply to local air heating units, said condenser having a fluid outletconnection and a fluid return connection; a first thermostat in one ofsaid connections; an evaporator for chilling fluid for supply to localair cooling units, said evaporator having a fluid outlet connection anda fluid return connection, a second thermostat in one of saidconnections of said evaporator; a first potentiometer having a slideradjusted by said first thermostat; a second potentiometer having aslider adjusted by said second thermostat; means connecting saidcompressor, said condenser and said evaporator in a closed refrigerationcircuit; a heat sink exchanger; a balancing relay having first andsecond windings, one end of said first winding being connected to oneend of said first potentiometer, the other end of said first windingbeing connected to one end of said second potentiometer, one end of saidsecond winding being connected to the other end of said firstpotentiometer, the other end of said second winding being connected tothe other end of said second potentiometer; electric supply linesconnected to said sliders; a first switch closed by said relay when thecurrent through said first winding is larger than the current throughsaid second winding; a second switch closed by said relay when thecurrent through said second winding is larger than the current throughsaid first winding; means for routing liquid refrigerant from saidcondenser to said heat exchanger, and for routing gas from said heatexchanger to said compressor; means including said first switch, whenclosed, for energizing said last mentioned means; means for routingdischarge gas from said compressor to said heat exchanger, and forrouting liquid refrigerant from said heat exchanger to said evaporator;and means including said second switch, when closed, for energizing saidlast mentioned means.

31. A heat pump as claimed in claim 30 in which a third potentiometer isprovided and which has a slider adjusted by said first thermostat; inwhich a fourth potentiometer is provided and which has a slider adjustedby said second thermostat; in which said supply lines are connected tosaid sliders of said third and fourth potentiometers; in which a secondbalancing relay is provided and which has third and fourth windings;means including switches closed when said first switch is closed forconnecting one end of said third winding to one end of said thirdpotentiometer and for connecting one end of said fourth winding to theother end of said third potentiometer; means including switches closedwhen said second switch is closed for connecting said one end of saidthird winding to one end of said fourth potentiometer and for connectingsaid one end of said fourth winding to the other end of said fourthpotentiometer; in which a fifth potentiometer is provided with its endsconnected to the other ends of said third and fourth windings; in whicha reversible motor having forward and reverse field windings, and havinga rotor connected to move the slider of said fifth potentiometer, isprovided; in which said second relay has a third switch which closeswhen the current through said third winding is larger than the currentthrough said fourth winding, and has a fourth switch which closes whenthe current through said fourth winding is larger than the currentthrough said third winding; means including said third switch forenergizing one of said windings of said motor, means including saidfourth switch for energizing the other one of said windings of saidmotor; in whichsaid compressor has a plurality of loaders-unloaders; inwhich a plurality of switches, one for each of said loaders-unloaders,is provided with said switches of said plurality being arranged to beclosed in succession when said rotor rotates in one direction, and to beopened in succession when said rotor rotates in the opposite direction;in which said loaders-unloaders are provided with solenoids foradjusting said loaders-unloaders to loading or unloading positions; andin which means including said last mentioned switches is provided forenergizing said solenoids.

References Cited by the Examiner UNITED STATES PATENTS ROBERT A. OLEARY,Primary Examiner.

1. A HEAT PUMP FOR COOLING INDOOR AIR IN A PORTION OF A BUILIDING ANDSIMULTANEOUSLY HEATING INDOOR AIR IN ANOTHER PORTION OF THE BUILDING,COMPRISING A REFRIGERANT COMPRESSOR; A CONDENSER FOR HEATING FLUID FORSUPPLY TO LOCAL AIR HEATING UNITS, AND HAVING ITS REFRIGERANT INLETCONNECTED TO THE DISCHARGE SIDE OF SAID COMPRESSOR; AN EVAPORATOR FORCHILLING FLUID FOR SUPPLY TO LOCAL AIR COOLING UNITS, AND HAVING ITSREFRIGERANT INLET CONNECTED TO THE REFRIGERANT OUTLET OF SAID CONDENSER;A SURGE DRUM HAVING A GAS OUTLET CONNECTED TO THE SUCTION SIDE OF SAIDCOMPRESSOR, AND HAVING A GAS AND UNEVAPORATED LIQUID INLET CONNECTED TOTHE REFRIGERANT OUTLET OF SAID EVAPORATOR; A PUMP HAVING AN INLETCONNECTED TO RECEIVE LIQUID REFRIGERANT FROM SAID DRUM, AND HAVING ANOUTLET CONNECTED TO SAID INLET OF SAID EVAPORATOR; A HEAT SINKEXCHANGER, AND HAVING ONE SIDE CONNECTED TO SAID INLET OF SAIDEVAPORATOR AND TO SAID OUTLET OF SAID PUMP; REVERSAL VALVE MEANSCONNECTED TO SAID DISCHARGE SIDE OF SAID COMPRESSOR, TO THE OTHER SIDEOF SAID HEAT EXCHANGER, AND TO SAID INLET OF SAID DRUM; MEANS WHEN THECOOLING LOAD IS GREATER THAN THE HEATING LOAD FOR ADJUSTING SAID VALVEMEANS TO ROUTE GAS FROM SAID DISCHARGE SIDE OF SAID COMPRESSOR TO SAIDOTHER SIDE OF SAID HEAT EXCHANGER, AND FOR ROUTING LIQUID FROM SAID PUMPTO SAID INLET OF SAID EVAPORATOR; AND MEANS WHEN THE HEATING LOAD ISGREATER THAN THE COOLING LOAD FOR ROUTING LIQUID FROM SAID PUMP TO SAIDONE SIDE OF SAID HEAT EXCHANGER, AND FOR ADJUSTING SAID VALVE MEANS TOROUTE GAS AND UNEVAPORATED LIQUID FROM SAID OTHER SIDE OF SAID HEATEXCHANGER TO SAID INLET OF SAID DRUM.